As shown in Figure 13b), the implementation will modify the existing SLIP/CSLIP implementation, Serial Lines IP, which is commonly used for point-to-point serial connections running TCP/IP. The modification is mainly around the packet format which makes DUAL a multi-point protocol, the DUAL packet format is explained earlier in this document.
Figure : Protocol stack with a) DUAL/CSLIP and b) SLIP/CSLIP
Figure 13b) also shows the interfaces which have to be modified to replace the SLIP with DUAL. Note that most of the modification is going to be within interfaces 1 and 2. Figure 13a) shows how the new protocol stack will look like with DUAL and CSLIP.
The security portion of the protocol stack is shown with dotted line in figure 13a). This part will be implemented after the DUAL is operational. The security portion is a sublayer at the IP layer, and will be implemented using the IP Security Protocol (see [Ioannidis \& Blaze 93] for details on the swIPe proposal).
IPSEC provides confidentiality, integrity and authentication of network traffic, and can be used to provide both end-to-end and intermediate-hop security. It is planned to incorporate an implementation of swIPe (see [Ioannidis \& Blaze ]) with simple policy and key management facilities. It is hoped to develop the key management aspects for large networks and have the granularity for the policy management.